In an optical lens such as a spectacle plastic lens, an antireflection film is coated on the surfaces thereof. The antireflection film is generally formed by use of an inorganic oxide such as ZrO.sub.2 or SiO.sub.2. Since the inorganic oxide used for forming the antireflection film has an inferior property in terms of water repellency or oil repellency, the surfaces of the optical lens applied with the antireflection film are liable to become dirty due to sweat or finger marks, a sort of oil and the like. Also, once these dirty marks adhered to the surfaces of the optical lens, it was difficult to remove them. Accordingly, the optical lens has been desired to have a dirt-prevention characteristic onto the surfaces thereof. Conventionally, in order to solve this problem, a water repellent film has been deposited on the above-mentioned antireflection film formed on the surfaces of the optical lens (for example, disclosed in the publications of JP-A-5-215905, JP-A-60-221470 and JP-A-4-218538). As conventional methods of forming the water repellent film on the surface of the optical lens, a dipping method, a vacuum evaporation method utilizing heat evaporation or a CVD method have been utilized.
Furthermore, in the recent methods of fabricating the optical lenses, a technology for depositing the water repellent film onto the surface of the lenses by utilizing a vacuum evaporation method in a final process has been proposed. In forming the water repellent film by the vacuum evaporation method, a plurality of optical lens base materials (in unit of a lot) are set on a circular planar holder which is rotatable, and the water repellent films are deposited on the optical lens base materials in every lot while the holder is rotating.
Further, in recent years, as a system for depositing the antireflection film on the surfaces of the optical lens, it has been proposed to use a deposition system for depositing the antireflection film by utilizing a sputtering method which is one of semiconductor manufacturing technologies. In this sputtering film deposition system, a plurality of optical lenses are arranged on a lens tray so that the both sides of the lenses can be simultaneously deposited by the sputtering method, and practically, the both sides of the optical lenses on the lens tray which is set to be rotatable freely in a sputtering chamber are simultaneously deposited with the antireflection film by the sputtering method using two targets disposed in the upper and lower sides of the lens tray.
And then, as mentioned above, the process of forming the water repellent film is carried out as the final process after the process of depositing the antireflection film. The plurality of optical lenses, each of which has the antireflection films formed on the both surfaces thereof respectively, are carried out from the sputtering deposition chamber with the state of being set on the lens tray, and thereafter they are carried in a vacuum processing chamber for forming the water repellent film. As the arrangement state of the optical lenses, they are supported to be horizontal on the lens tray and their both surfaces are kept to face to upper and lower sides respectively owing to the structure of the lens tray. Accordingly, it is also desired that the both sides of the optical lenses are simultaneously deposited with the water repellent film in the final process for forming the water repellent film. Thereby, it can be expected that efficiency in the process of forming the water repellent film is improved and further a performance characteristic of the water repellent film is improved.
Further, conventionally, it has been considered that a thickness distribution of the water repellent film formed by the vacuum evaporation method is satisfactory. However, when applying the vacuum evaporation method to the thin film formation for a spectacle lens with a meniscus shape, it is required to realize a film thickness distribution having an uniformity with a higher precision without being affected by a curvature of the lens. If there is dispersion on the film thickness of the water repellent films, it is difficult to keep the quality and so on of the optical lens in a desired specific level because the dispersion concerning interference characteristics or qualities among optical products are occurred.
An object of the present invention is to provide a both sides simultaneous water repellency processing mechanism capable of improving the efficiency of the water repellency processing by the process of forming the water repellent film onto the both surfaces of the optical lens simultaneously and thereby improving work efficiency and productivity.
Another object of the present invention is to decrease the film thickness difference in a water repellent film or among the films deposited on the surfaces of the plurality of optical lenses set on the holder by utilizing the vacuum evaporation method, and to make the film thickness distribution uniform with a high precision.